Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.
Aegis Authenticator - Aegis Authenticator is a free, secure and open source app to manage your 2-step verification tokens...
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.
Authy - Best rated Two-Factor Authentication smartphone app for consumers, simplest 2fa Rest API for developers and a strong authentication platform for the enterprise.
Memrise - Learn a new language with games, humorous chatbots and over 30,000 native speaker videos.
OTP Auth - The app for calculating one-time-passwords on iPhone and iPad.